The Million Pound Deposit

This 1929 novel by E. Phillips Oppenheim neatly describes some of the frothy financial dealings of the late stage of the roaring 20s in England and centered around a commercial chemical formula. The formula for the process is carefully guarded from its own employees, but is stolen one night by a band of five adventurers who plan to ransom it for 1 million pounds. Two men are killed during the robbery. Plans to ransom the process are put on hold, and the documents are deposited in a London Safe Deposit company. Meanwhile, the managing director of Boothroyds, Sir Matthew Parkinson, has been forced to sell some of his shares to cover debts. His lovely daughter Grace is the only person who seems concerned about the welfare of the company and its workers.